Magnetic resonance imaging for verifying hip fracture diagnosis why, when and how?

Magnetic Resonance Neuroimaging Contrast Agents of Nanomaterials

Since the early 1980s when MRI imaging technology was put into clinical use, the number of MRI clinical tests has steadily increased by more than 10% every year. At the same time, exogenous MRI contrast agents have also been developed with the development of MRI technology. However, there are still challenges in the preparation of contrast agents for magnetic resonance imaging, such as how to prepare high-efficiency contrast agents with high stability and low biological toxicity. In order to study the contrast agent with simple preparation method, low cost, and good imaging effect, a magnetic resonance contrast agent was prepared by magnetic nanoparticles. By acting on magnetic resonance imaging detection method, and using polymer ligands to synthesize magnetic nanoparticles, experiments and tests of P(MA-alt-VAc) polymer ligand-modified magnetic nanoparticles were carried out. The experimental results showed that when nanoparticles containing different iron ion concentrations were incubated with DC 2.4 normal cells for 48 hours, the cell viability was still higher than 80% at concentrations up to 200 μm. It shows that the nanoparticle has high cell activity and good biological adaptability. The transverse relaxation (r²) value of the nanoparticles in aqueous solution at 37°C and 1.5 T magnetic field is 231.1 m⁻¹ s⁻¹, which is much higher than that of PTMP-PMAA (r² = 35.1 mM⁻¹ s⁻¹), which is also more than five times the relaxation of SHU-555C (r² = 44 mM⁻¹ s⁻¹). It shows that the nanoparticles prepared in this paper have good effect and can be used as a contrast agent in human brain for magnetic resonance imaging.

Clinical outcomes of patients with Garden I and II femoral neck fractures as verified on MRI: a retrospective case series

Background

Between 2 to 10% of non-displaced femoral neck fractures (nFNF) cannot be diagnosed on plain radiographs and require further imaging investigation to be detected or verified. These fractures are referred to as occult hip fractures. This study aimed to report treatment failures, reoperations and mortality in a consecutive series of occult femoral neck fractures (FNF) treated with internal fixation (IF).

Methods

A retrospective multicenter study was performed based on a consecutive series of patients aged ≥ 60 years with an occult magnetic resonance imaging (MRI) verified Garden I and II FNF sustained after a trauma and treated with primary IF. We included 93 patients with a minimum 2-year follow-up. Radiographic assessment encompassed pre- and postoperative tilt, implant inclination, MRI and treatment failure. Data on reoperation and mortality were collected. Treatment failure was defined as fixation failure, nonunion, avascular necrosis or posttraumatic osteoarthritis.

Results

The study comprised of 93 patients (72% women, 67/93) with a mean age of 82 (range, 60–97) years. Overall, 6 (6%) patients had major reoperations. 2 (2%) had minor reoperations. One-month mortality was 7%, 1-year mortality was 20% and 2-year mortality was 31%.

Conclusion

This multicenter cohort study identifies a subgroup of elderly patients with MRI verified Garden I and II FNFs sustained after trauma, i.e. occult fractures. These fractures seem to have a lower complication rate compared to nFNF identified on plain radiographs.

Level of evidence

Prognostic Level V. See Instructions to Authors for a complete description of levels of evidence.

Reviewing acute hip fractures in adults

ABSTRACT

Hip fractures are considered a significant public health issue, representing a substantial burden on our healthcare system and society. They are one of the leading causes of disability among older adults, especially women. Globally, an estimated 18% of women and 6% of men will be affected by hip fractures at some time in life. Hip fractures are a major cause of long-term disability among older adults and more significant than mortality, as only 60% of patients regain their preinjury level of mobility. This has detrimental effects on quality of life and activities of daily living, imposing a level of dependence that has personal, social, and systemic consequences.

Magnetic Resonance Imaging has Better Accuracy in Detecting New-Onset Rib Fractures as Compared to Computed Tomography

Background

The aim of this study was to explore the magnetic resonance imaging (MRI) manifestations of new-onset rib fractures and determine the utility of MRI through a comparative study of MRI and computed tomography (CT).

Material/Methods

Twenty-one patients with mild chest trauma who sought medical care from February 2019 to June 2020 were included in this study. The patients were subjected to CT and MRI scanning within 2 weeks after the trauma, and CT rescanning was scheduled 4–8 weeks later to classify rib fractures and determine the diagnostic accuracy of MRI and CT for new-onset rib fractures.

Results

Seventy-seven rib fractures were confirmed by CT rescanning, of which 72 (93.51%) were type I fractures and 5 (6.49%) were type II. MRI identified 76 fractures, of which 3 were false positive, with the diagnostic accuracy rate of 91.25% and sensitivity rate of 94.81%. Among them, type I fractures (n=71, 3 were false positive) showed the MRI “sandwich” sign (heterogeneous high-signal shadow within bone marrow of the inner layer, low-signal bony cortex of the middle layer, and high-signal subperiosteal effusion of the outer layer) in T2-weighted fat-suppressed sequences; type II fractures (n=5) displayed intramedullary high-signal intensities and no subperiosteal effusion. Forty-four fractures (all type I) were discovered in the initial CT examination, and the corresponding diagnostic accuracy rate and sensitivity rate were 57.14%, which were lower than that of MRI.

Conclusions

MRI is highly sensitive for new-onset rib fractures, especially type I, so it is a preferred method for patients with mild chest trauma.

Use of Advanced Imaging for Radiographically Occult Hip Fracture in Elderly Patients: A Systematic Review and Meta-Analysis

Background The overall rate of hip fractures not identified on radiographs but that require surgery (ie, surgical hip fractures) remains unclear in elderly patients who are suspected to have such fractures based on clinical findings. Moreover, the importance of advanced imaging in these patients has not been comprehensively assessed. Purpose To estimate the frequency of radiographically occult hip fracture in elderly patients, to define the higher-risk subpopulation, and to determine the diagnostic performance of CT and bone scanning in the detection of occult fractures by using MRI as the reference standard. Materials and Methods A literature search was performed to identify English-language observational studies published from inception to September 27, 2018. Studies were included if patients were clinically suspected to have hip fracture but there was no radiographic evidence of surgical hip fracture (including absence of any definite fracture or only presence of isolated greater trochanter [GT] fracture). The rate of surgical hip fracture was reported in each study in which MRI was used as the reference standard. The pooled rate of occult fracture, diagnostic performance of CT and bone scanning, and strength of evidence (SOE) were assessed. Results Thirty-five studies were identified (2992 patients; mean age, 76.8 years ± 6.0 [standard deviation]; 66% female). The frequency of radiographically occult surgical hip fracture was 39% (1110 of 2835 patients; 95% confidence interval [CI]: 35%, 43%) in studies of patients with no definite radiographic fracture and 92% (134 of 157 patients; 95% CI: 83%, 98%) in studies of patients with radiographic evidence of isolated GT fracture (moderate SOE). The frequency of occult fracture was higher in patients aged at least 80 years (44%, 529 of 1184), those with an equivocal radiographic report (58%, 71 of 126), and those with a history of trauma (41%, 977 of 2370) (moderate SOE). CT and bone scanning yielded comparable diagnostic performance in the detection of radiographically occult hip fracture (P = .67), with a sensitivity of 79% and 87%, respectively (low SOE). Conclusion Elderly patients with acute hip pain and negative or equivocal findings at initial radiography have a high frequency of occult hip fractures. Therefore, the performance of advanced imaging (preferably MRI) may be clinically appropriate in all such patients. © RSNA, 2020 Online supplemental material is available for this article.

Is There a Role for CT Pan-Scans in the Initial Workup of Fragility Fracture Patients?

Introduction:

Computed tomography (CT) pan-scans have become increasingly commonplace as part of the initial diagnostic workup for patients sustaining traumatic injuries. They have proven effective in improving diagnostic accuracy in those with high-energy mechanisms of injury. However, the utility of pan-scans in the geriatric population sustaining low-energy traumatic injuries remains unproven.

Methods:

A retrospective review was conducted of patients who sustained a fragility fracture at a level-1 trauma center over a 15-month period. Radiologist interpretations of any CT pan-scans were reviewed for acute findings, and charts were reviewed for resulting changes in orthopedic and nonorthopedic management. Additionally, mechanism of injury, definitive management, time to surgery, length of stay, level of care at discharge, and demographic data were compared against similar patients who did not receive a pan-scan.

Results:

Of the 109 patients who underwent a CT pan-scan, 1 (0.92%) had a change in orthopedic treatment. Twelve (11.01%) patients had changes to their nonorthopedic management. In addition, 14 other patients had one or more consultations obtained based on pan-scan results that did not result in any change in management. Discussion: This study found that only 1 of the included patients had a change in orthopedic management and 12 had a change in nonorthopedic management, despite over half of the study population being found to have additional findings. Furthermore, patients who underwent a pan-scan did not have expedited surgical intervention or earlier discharges compared to those who were not pan-scanned.  

Conclusion:

This study demonstrates whole-body CT imaging provides little benefit in geriatric patients who sustain fragility fractures and should be utilized judiciously and in a targeted fashion instead of as a routine part of trauma surgery or emergency department protocol in this patient population.

Level of Evidence:

Level III Retrospective Study.

Improving the Diagnosis of Ipsilateral Femoral Neck and Shaft Fractures: A New Imaging Protocol

BACKGROUND

Despite increased awareness of ipsilateral femoral neck fractures in patients with high-energy femoral shaft fractures and advanced imaging with thin-cut high-resolution computed tomography (CT), failure of diagnosis remains problematic. The purpose of the present study was to determine if the preoperative diagnosis of ipsilateral femoral neck fractures in patients with high-energy femoral shaft fractures can be improved with magnetic resonance imaging (MRI) compared with radiographic and CT imaging.

METHODS

In response to delayed diagnoses of femoral neck fractures despite thin-cut high-resolution CT, our institutional imaging protocol for acute, high-energy femoral shaft fractures was altered to include rapid limited-sequence MRI to evaluate for occult femoral neck fractures. All patients received standard radiographic imaging as well as thin-cut high-resolution pelvic CT imaging upon presentation. Rapid limited-sequence MRI of the pelvis was obtained to evaluate for an occult femoral neck fracture.

RESULTS

Thirty-seven consecutive patients with 39 acute, high-energy femoral shaft fractures resulting from blunt trauma were included. The average age of the patients was 29.1 years (range, 14 to 82 years). Ten (25.6%) of the 39 femoral shaft fractures were open. Two femoral shaft fractures (5.1%) were associated with ipsilateral femoral neck fractures that were detected on radiographs, and no MRI was performed. None of the remaining 37 femoral shaft fractures were associated with a femoral neck fracture that was identified on CT imaging. Thirty-three (89.2%) of 37 patients underwent pelvic MRI to evaluate the ipsilateral femoral neck. Four (12.1%) of those 33 patients were diagnosed with a femoral neck fracture (2 complete, 2 incomplete) that was not identified on thin-cut high-resolution CT or radiographic imaging.

CONCLUSIONS

Rapid limited-sequence MRI of the pelvis for patients with femoral shaft fractures identified femoral neck fractures that were not diagnosed on thin-cut high-resolution CT in 12% of our patients. Our results suggest that the frequency of femoral neck fractures may be underrepresented on CT imaging; rapid limited-sequence MRI was feasible without delaying definitive treatment even in polytraumatized patients.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI

PURPOSE

To determine the margins of non-inferiority of the sensitivity of CT and the sample size needed to test the non-inferiority of CT in comparison with MRI.

MATERIALS AND METHODS

During a 2-year period, elderly patients with suspected radiographically occult post-traumatic bone injuries were investigated by CT and MRI in two institutions. Four radiologists analyzed separately the CT and MRI examinations to detect post-traumatic femoral injuries. Their sensitivities at CT (SeCT) and MRI (SeMRI) were calculated with the reference being a best valuable comparator (consensus reading of the MRI and clinical follow-up). ROC analysis followed by an exact test (Newcombe's approach) was performed to assess the 95% confidence interval (CI) for the difference SeCT-SeMRI for each reader. A sample size calculation was performed based on our observed results by using a one-sided McNemar's test.

RESULTS

Twenty-nine out of 102 study participants had a post-traumatic femoral injury. SeCT ranged between 83 and 93% and SeMRI ranged between 97 and 100%. The 95% CIs for (SeCT-SeMRI) were [- 5.3%, + 0.8%], (p^R1 = 0.1250), [- 4.5%; + 1.2%] (p^R2 = 0.2188), [- 3.4%; + 1.1%] (p^R3 = 0.2500) to [- 3.8%; + 1.6%] (p^R4 = 0.3750) according to readers, with a lowest limit for 95% CIs superior to a non-inferiority margin of (- 6%) for all readers. A population of 440 patients should be analyzed to test the non-inferiority of CT in comparison with MRI.

CONCLUSION

CT and MRI are sensitive for the detection of radiographically occult femoral fractures in elderly patients after low-energy trauma. The choice between both these modalities is a compromise between the most available and the most sensitive technique.

KEY POINTS

• The sensitivity of four separate readers to detect radiographically occult post-traumatic femoral injuries in elderly patients after low-energy trauma ranged between 83 and 93% at CT and between 97 and 100% at MRI according to a best valuable comparator including MRI and clinical follow-up. • CT is a valuable alternative method to MRI for the detection of post-traumatic femoral injuries in elderlies after low-energy trauma if a 6% loss in sensitivity can be accepted in comparison with MRI. • The choice between CT and MRI is a compromise between the most available and the most sensitive technique.

Detecting intertrochanteric hip fractures with orthopedist-level accuracy using a deep convolutional neural network

OBJECTIVE

To compare performances in diagnosing intertrochanteric hip fractures from proximal femoral radiographs between a convolutional neural network and orthopedic surgeons.

MATERIALS AND METHODS

In total, 1773 patients were enrolled in this study. Hip plain radiographs from these patients were cropped to display only proximal fractured and non-fractured femurs. Images showing pseudarthrosis after femoral neck fracture and those showing artificial objects were excluded. This yielded a total of 3346 hip images (1773 fractured and 1573 non-fractured hip images) that were used to compare performances between the convolutional neural network and five orthopedic surgeons.

RESULTS

The convolutional neural network and orthopedic surgeons had accuracies of 95.5% (95% CI = 93.1-97.6) and 92.2% (95% CI = 89.2-94.9), sensitivities of 93.9% (95% CI = 90.1-97.1) and 88.3% (95% CI = 83.3-92.8), and specificities of 97.4% (95% CI = 94.5-99.4) and 96.8% (95% CI = 95.1-98.4), respectively.

CONCLUSIONS

The performance of the convolutional neural network exceeded that of orthopedic surgeons in detecting intertrochanteric hip fractures from proximal femoral radiographs under limited conditions. The convolutional neural network has a significant potential to be a useful tool for screening for fractures on plain radiographs, especially in the emergency room, where orthopedic surgeons are not readily available.

Patients with Clinically Suspected but Unproven Hip Fractures, Who Require Cross-Sectional Imaging, Are Best Initially Admitted under Geriatrician-Led Care-A Retrospective Review

Patients with suspected hip fractures who require further imaging to confirm or disprove the diagnosis may be admitted to orthopaedic or medical departments. We aim to provide evidence regarding the appropriate admission pathway for such patients. This is a retrospective study of all suspected hip fracture patients receiving second-line imaging between 1 January 2015 to 30 June 2016 in one hospital trust. Information was gained from hospital records to determine indication and result of imaging, eventual diagnoses, length of stay, and inpatient mortality. During the study period, 126 patients underwent cross-sectional imaging for clinically suspected but unproven hip fractures. Of these, 27% were positive for hip fractures (n = 34, 3.2% of hip fracture admissions) whilst the remainder were negative. Of the patients without hip fractures, 50 (54%) had a concomitant medical discharge diagnosis. Thirty-one different diagnoses were found in this cohort. This research provides evidence for geriatrician-led admission of patients with suspected but unproven hip fracture, due to the frailty and medical requirements of this patient group.